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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 16 |
| 5 | 118 |
| 6 | 1077 |
| 7 | 11486 |
| 8 | 138444 |
| 9 | 1847148 |
| 10 | 26912226 |
| 11 | 424290217 |
| 12 | 7194012328 |
| 13 | 130641675418 |
| 14 | 2534008088656 |
| 15 | 52404312807800 |
| 16 | 1154031769467768 |
| 17 | 27034986095711172 |
| 18 | 673063391032594741 |
| 19 | 17786452294614118713 |
| 20 | 498174223396072711297 |
| 21 | 14762117810503938465521 |
| 22 | 461836676823537625928868 |
[1,1,1,3,16,118,1077,11486,138444,1847148, 26912226,424290217,7194012328,130641675418, 2534008088656,52404312807800,1154031769467768, 27034986095711172,673063391032594741, 17786452294614118713,498174223396072711297, 14762117810503938465521,461836676823537625928868] |